android拍照保存全尺寸图片

向右看齐 2022-09-26 03:59 305阅读 0赞

这种保存图片的好处：在有限的内存下，管理许多全尺寸的图片会很棘手。如果发现应用在展示了少量图片后消耗了所有内存，我们可以通过缩放图片到目标视图尺寸，之后再载入到内存中的方法，来显著降低内存的使用。

demo已解决的问题：在onCreate()得到控件的宽度和长度，

在onCreate()方法中调用

ViewTreeObserver vto = image.getViewTreeObserver();
    
    vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
        public boolean onPreDraw() {
            targetH = image.getMeasuredHeight();
            targetW = image.getMeasuredWidth();
    
            return true;
        }
    });

如果希望照片对我们的应用而言是私有的，那么可以使用[getExternalFilesDir()][getExternalFilesDir]提供的目录

如果希望照片对所有应用共享，那么可以使用[getExternalStoragePublicDirectory()提供的目录][getExternalStoragePublicDirectory]

首先加一个写的权限

按钮点击

button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            //判断是否有相机 if (intent.resolveActivity(getPackageManager()) != null) {
                File photoFIle=null;
                try {
                    photoFIle = createImageFile();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                if (photoFIle != null) {
                    //怎么将拍好的照片保存在sd卡中？ /* 首先在sd卡中创建一个空的.jpg文件，然后获取创建好的.jpg的uri, 接着通过intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFIle)); MediaStore.EXTRA_OUTPUT这个表示照相完成后保存图片在uri这个.jpg文件中 */ intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFIle));
                    gallerAddPic();
                    startActivityForResult(intent,REQUEST_IMAGES);
                }
    
            }
        }
    });

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_IMAGES && resultCode == RESULT_OK) {
    
            setPic();
         /* Bundle bundle=data.getExtras(); Bitmap bitmap = (Bitmap) bundle.get("data"); image.setImageBitmap(bitmap);*/ }
    }

private void setPic(){
        Log.d("test", targetH+";;;");
        BitmapFactory.Options bmOptions=new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds=true;//设置inJustDecodeBounds为true后，decodeFile并不分配空间，但可计算出原始图片的长度和宽度 //bmOptions指向mCurrentPhotoPaht路径中的图片 BitmapFactory.decodeFile(mCurrentPhotoPaht, bmOptions);
    
        //之所以phtotW=0是因为mCurrentPhotoPaht的路径出错，找不到拍照后保存下的图片 float photoW=bmOptions.outHeight;
        float photoH=bmOptions.outHeight;
        Log.d("test", "photoW" + photoW);
        float scaleFactor = Math.min(photoW / targetW, photoH / targetH);//设置缩放比例 bmOptions.inJustDecodeBounds=false;// bmOptions.inSampleSize=(int) scaleFactor;
    
        bmOptions.inPurgeable=true;//inPurgeable:设置为True时,表示系统内存不足时可以被回 收 Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPaht, bmOptions);
        image.setImageBitmap(bitmap);
    }
    //触发系统的Media Scanner，将我们的照片添加到Media Provider的数据库中，就是将照片添加到相册，拍照后你就可以在相册中看到 private void gallerAddPic(){
        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        Log.d("test", mCurrentPhotoPaht + ":gallerAddPic");
        File f = new File(mCurrentPhotoPaht);
        Uri contentUri = Uri.fromFile(f);
        mediaScanIntent.setData(contentUri);
        this.sendBroadcast(mediaScanIntent);
    }
    private File createImageFile() throws IOException{
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(imageFileName, ".jpg", storageDir);
        mCurrentPhotoPaht=image.getAbsolutePath();
        Log.d("test", mCurrentPhotoPaht);
        return image;
    } 
     
     //保存路径长度，宽度，防止重建Activity时长度，宽度，mCureentPhotoPaht出错 @Override
    protected void onSaveInstanceState(Bundle outState) {
        outState.putString("path",mCurrentPhotoPaht);
        outState.putInt("w",targetW);
        outState.putInt("h",targetH);
        Log.d("test", "onSaveInstance"+mCurrentPhotoPaht);
        super.onSaveInstanceState(outState);
    }
    
    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        mCurrentPhotoPaht = savedInstanceState.getString("path");
    
        targetH = savedInstanceState.getInt("h");
        targetW = savedInstanceState.getInt("w");
        Log.d("test", "onresotre:" + mCurrentPhotoPaht);
        super.onRestoreInstanceState(savedInstanceState);
    }

[getExternalFilesDir]: http://developer.android.com/reference/android/content/Context.html#getExternalFilesDir%28java.lang.String%29
[getExternalStoragePublicDirectory]: http://developer.android.com/reference/android/os/Environment.html#getExternalStoragePublicDirectory%28java.lang.String%29